Lighting systems used to illuminate the interiors of cabinet display cases such as refrigerated display coolers can be found in most any grocery or convenience store. Originally such display refrigerators were lit with incandescent lamps very much like a typical refrigerator. The move to florescent lamps was an improvement that decreased the amount of heat generated by the lighting system. Most recently the use of light emitting diodes (LEDs) has been introduced to further decrease heat generation and to reduce the amount of electrical consumption.
The main problem that still exists when using LEDs in a cabinet display case is configuring the lights to illuminate product displayed therein. Light emitting diodes have a generally cone shaped light output when considering their intensity which means that much of the light output will be concentrated unevenly upon the displayed products if not directed into other areas besides the product. Methods to achieve the goal of even distribution of light have included: mounting the LEDs in a multitude of locations within the cabinet display case; physically orienting the LEDs toward the product; and use of reflective surfaces to redistribute the LEDs light output.
One solution taught by Wing in U.S. Pat. No. 7,338,180 is to place the LEDs on the end of the shelves that hold the product to be illuminated but this presents the problem of increasing or decreasing the amount of light based on the number of shelves used. It also requires that each shelf have wires running to and from it which creates a messy tangle when reconfiguring shelves. The only alternative is to wire the back of the cabinet with electrical connectors at each and every shelf support mount which would create a major cost deterrent due to the number of components and the more involved manufacturing method.
Other solutions attempted to mount the lights in the door but these solutions did not provide for proper lighting of the product once the cabinet door was open. The light sources also incurred repeated movement and shocks with the door opening and closing. These shocks have little effect on the LEDs but do have a detrimental effect on the wiring for the system. The wiring for door mounted LEDs itself had, by necessity, to be placed near the door axis which increased the instances of the wires becoming wedged in the door seals and therefore compromising the thermal integrity of the cabinet display case.
A solution put forth by Artwohl in U.S. Patent Application No. 2007/0195535 was to use an array of LEDs mounted in the mullions between or at the sides of refrigerated cabinet doors. This florescent light replacement solution had been anticipated by such inventors as Chen in U.S. Pat. No. 7,331,689 or Rudick in U.S. Pat. No. 6,550,269 but both lacked the ability to direct the necessary light toward the product in an even and consistent manner. Artwohl tried to improve upon Chen through the use of reflective surfaces but only a small percentage of the light could be directed to the most visible parts of the products arranged on the shelves.
Therefore what is needed is an LED generated light source system for use in a display cabinet that can be mounted in a mullion between doors, that could be easily and simply installed, that emits the majority of the light produced by the LEDs in an even and consistent distribution towards the product that is displayed on the shelves within the cabinet.